[swift-evolution] [Review] SE-0073: Marking closures as executing exactly once

[Andrew Bennett]

Hi Dave,

Sorry, Dave, sending a second time as I forgot to Reply-All.

I agree, this proposal doesn't allow multiple closures where only one of
them should be run, and it should only be run once. I personally don't
think lacking that functionality is worth blocking this proposal for,
another proposal can be built on top of this if it is desired.

These cases can also be handled by a more meaningful if/switch statement,
using @noescape(once), for example:
  let x: Int
  functionThatCallsAClosure(someTest()) { x = $0 ? 1 : 2 }

On Sat, May 7, 2016 at 6:24 AM, Dave Abrahams via swift-evolution <
swift-evolution at swift.org> wrote:

>
> on Tue May 03 2016, Chris Lattner <swift-evolution at swift.org> wrote:
>
> > Hello Swift community,
> >
> > The review of "SE-0073: Marking closures as executing exactly once"
> > begins now and runs through May 9. The proposal is available here:
> >
> >
> https://github.com/apple/swift-evolution/blob/master/proposals/0073-noescape-once.md
> >
> > Reviews are an important part of the Swift evolution process. All
> reviews should be sent to the swift-evolution mailing list at
> >
> >       https://lists.swift.org/mailman/listinfo/swift-evolution
> >
> > or, if you would like to keep your feedback private, directly to the
> review manager.
> >
> > What goes into a review?
> >
> > The goal of the review process is to improve the proposal under review
> > through constructive criticism and contribute to the direction of
> > Swift. When writing your review, here are some questions you might
> > want to answer in your review:
> >
> >       * What is your evaluation of the proposal?
>
> I think it's of questionable importance and doesn't generalize well.
> For example, you can't use this to construct something like
>
>   var x: Int
>   functionThatActsLikeIf( someTest(), then: { x = 1 }, else: { x = 2} )
>
> If you need to initialize something in an outer scope with something
> computed by a closure, it's much better to arrange something like this:
>
>   var x = functionThatActsLikeIf( someTest(), then: {  1 }, else: { 2 } )
>
> --
> Dave
>
> _______________________________________________
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> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
>
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